Process for preparing 1-butene polymers

ABSTRACT

A process for obtaining 1-butene polymers comprising the step of contacting under polymerization conditions 1-butene and optionally ethylene, propylene or said alpha-olefin, in the presence of a catalyst system obtainable by contacting: a) a metallocene compound of formula (I): 
                         
wherein: M is an atom of a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements; p is an integer from 0 to 3; X, is a hydrogen atom, a halogen atom, or a hydrocarbon group; R 1  is a hydrocarbon group; R 2 , R 3  and R 6  are hydrogen atoms or hydrocarbon groups; R 4  and R 5  join to form a condensed saturated or unsaturaded 4–7 membered ring; and L is a divalent bridging group; and b) an alumoxane or a compound able to form an alkylmetallocene cation.

This application is the U.S. national phase of International ApplicationPCT/EP2003/012236, filed Nov. 3, 2003, claiming priority to EuropeanPatent Application 02080120.5 filed Dec. 4, 2002, and the benefit under35 U.S.C. 119(e) of U.S. Provisional Application No. 60/431,803, filedDec. 9, 2002; the disclosures of International ApplicationPCT/EP2003/012236, European Patent Application 02080120.5 and U.S.Provisional Application No. 60/431,803, each as filed, are incorporatedherein by reference.

The present invention relates to a process for polymerizing 1-butene byusing a substituted bridged bis-indenyl metallocene compound.

1-Butene polymers are well known in the art. In view of their goodproperties in terms of pressure resistance, creep resistance, and impactstrength, they are widely used for example in the manufacture of pipesfor metal pipe replacement, easy-open packaging and films.

The 1-butene (co)polymers are generally prepared by polymerizing1-butene in the presence of TiCl₃ based catalyst components togetherwith diethylaluminum chloride (DEAC) as cocatalyst. In some casesmixtures of diethyl aluminum iodide (DEAI) and DEAC are used. Thepolymers obtained, however, generally do not show satisfactorymechanical properties. Furthermore, in view of the low yields obtainablewith the TiCl₃ based catalysts, the 1-butene polymers prepared withthese catalysts have a high content of catalyst residues (generally morethan 300 ppm of Ti) which lowers the properties of the polymers andmakes necessary to carry out a subsequent deashing step.

1-Butene (co)polymers can also be obtained by polymerizing the monomersin the presence of a stereospecific catalyst comprising: (A) a solidcomponent comprising a Ti compound and an electron-donor compoundsupported on MgCl₂; (B) an alkylaluminum compound and, optionally, (C)an external electron-donor compound. A process of this type is disclosedin EP-A-172961 and WO99/45043.

Recently metallocene compounds have been used for producing 1-butenepolymers. In Macromolecules 1995, 28, 1739–1749,rac-dimethylsilylbis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichlorideand methylaluminoxane have been used for polymerizing 1-butene; even ifthe yield of the process is not indicated, the number average molecularweight (Mn) of the obtained polymers is very low.

In Macromol. Rapid Commun. 18, 581–589 (1997) rac andmeso-[dimethylsilylenebis(2,3,5-trimethyl-cyclopentadienyl)]zirconiumdichloride have been used for the polymerization of 1-butene; the yieldsof the process and the molecular weight of the obtained polymers arerather low.

More recently, in Macromolecules 2000, 33, 1955–1956Me₂Si(2-Me-4,5-BzoInd)₂ZrCl₂, Me₂Si(2-Me-4-PhInd)₂ZrCl₂ andMe₂Si(Ind)₂ZrCl₂ have been tested in the polymerization of 1-butene. Theobtained polymers possesses molecular weights higher than the onesdescribed in the previous documents, nevertheless they can be furtherimproved; moreover the activities of these catalysts are notsatisfactory, as shown in the comparative examples of the presentapplication.

WO 99/46270 relates to a process for synthesizing bridged metallocenecomplexes containing a neutral diene ligand, comprising the step ofcontacting a metal complex of formula MX₂D with a compound of formula(L—A—L)M″_(n) wherein M is titanium, zirconium or hafnium in the +2formal oxidation state; M″ is hydrogen, a group 1 metal cation, a group2 metal or zinc dication and the like; L is an anionic ligand bonded toA; A is a divalent bridge; X is a monovalent anionic leaving group and Dis a neutral substituted derivative of 1,3-butadiene. In example 14, acomplex of formula (d) was prepared

This compound is not used for polymerizing 1-butene.

Therefore it would be desirable to develop a process that allows toobtain 1-butene polymer with high molecular weight and in high yield.

An object of the present invention is a process for preparing 1-butenepolymers optionally containing up to 30% by mol of units derived from atleast one monomer selected from ethylene, propylene or an alpha olefinof formula CH₂═CHZ, wherein Z is a C₃–C₁₀ alkyl group, comprisingpolymerizing 1-butene and optionally ethylene, propylene or saidalpha-olefin, in the presence of a catalyst system obtainable bycontacting:

-   a) at least a metallocene compound of formula (I):

-    wherein:    -   M is a transition metal belonging to group 3, 4, 5, 6 or to the        lanthanide or actinide groups in the Periodic Table of the        Elements; preferably M is titanium, zirconium or hafnium;    -   p is an integer from 0 to 3, preferably p is 2, being equal to        the formal oxidation state of the metal M minus 2;    -   X, equal to or different from each other, are hydrogen atoms,        halogen atoms, R, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ groups,        wherein R is a linear or branched, saturated or unsaturated        C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl        or C₇–C₂₀ arylalkyl radical, optionally containing heteroatoms        belonging to groups 13–17 of the Periodic Table of the Elements;        or two X can optionally form a substituted or unsubstituted        butadienyl radical or a OR′O group wherein R′ is a divalent        radical selected from C₁–C₂₀ alkylidene, C₆–C₄₀ arylidene,        C₇–C₄₀ alkylarylidene and C₇–C₄₀ arylalkylidene radicals;        preferably X is a hydrogen atom, a halogen atom or a R group;        more preferably X is chlorine or a methyl radical;    -   R¹, equal to or different from each other, are linear or        branched, saturated or unsaturated C₁–C₂₀-alkyl,        C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or        C₇–C₂₀-arylalkyl radicals, optionally containing one or more        heteroatoms belonging to groups 13–17 of the Periodic Table of        the Elements; preferably R¹ is a C₁–C₂₀-alkyl radical; more        preferably it is a methyl or ethyl radical;    -   R², R³ and R⁶, equal to or different from each other, are        hydrogen atoms or linear or branched, saturated or unsaturated        C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl        or C₇–C₂₀-arylalkyl radicals, optionally containing one or more        heteroatoms belonging to groups 13–17 of the Periodic Table of        the Elements; preferably R², R³ and R⁶ are hydrogen atoms;    -   R⁴ and R⁵, form together a condensed saturated or unsaturaded        C₃–C₇-membered ring preferably a C₄–C₆-membered ring, optionally        containing heteroatoms belonging to groups 13–16 of the Periodic        Table of the Elements; every atom forming said ring being        substituted with R⁷ radicals; that means that the valence of        each atom forming said ring is filled with R⁷ groups, wherein        R⁷, equal to or different from each other, are hydrogen or        linear or branched, saturated or unsaturated C₁–C₂₀-alkyl,        C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or        C₇–C₂₀-arylalkyl radicals, optionally containing one or more        heteroatoms belonging to groups 13–17 of the Periodic Table of        the Elements; preferably R⁷ is a hydrogen atom or a linear or        branched, saturated or unsaturated C₁–C₂₀-alkyl radical; more        preferably it is a hydrogen atom or a methyl or ethyl radical;    -   L is a divalent bridging group selected from C₁-C₂₀ alkylidene,        C₃-C₂₀ cycloalkylidene, C₆-C₂₀ arylidene, C₇-C₂₀ alkylarylidene,        or a C₇-C₂₀ arylalkylidene radicals, optionally containing        heteroatoms belonging to groups 13–17 of the Periodic Table of        the Elements, or it is a silylidene radical containing up to 5        silicon atoms; preferably L is Si(R⁸)₂ wherein R⁸ is a linear or        branched, saturated or unsaturated C₁–C₂₀-alkyl,        C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or        C₇–C₂₀-arylalkyl radical; more preferably L is Si(CH₃)₂ or        SiPh₂;-   b) at least an alumoxane or a compound able to form an    alkylmetallocene cation; and-   c) optionally an organo aluminum compound.

Preferably the compound of formula (I) is in the racemic (rac) form.

Preferably the compound of formula (I) has formula (IIa) or (IIb)

wherein:

M, X, p, L, R¹, R², R³, R⁶ and R⁷ have the meaning described above.

Compounds of formula (I) can be prepared with a process comprising thefollowing steps:

-   a) contacting a ligand of formula (III)

-    and/or its double bond isomers    -   wherein R¹, R², R³, R⁴, R⁵, R⁶, and L have the meaning described        above with a base selected from T_(j)B, TMgT¹, sodium and        potassium hydride, metallic sodium and potassium, wherein B is        an alkaline or alkali-earth metal; and j is 1 or 2, j being        equal to 1 when B is an alkaline metal, preferably lithium, and        j being equal to 2 when B is an alkali-earth metal; T is a        linear or branched, saturated or unsaturated C₁–C₂₀ alkyl,        C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl or C₇–C₂₀        arylalkyl group, optionally containing one or more Si or Ge        atoms; preferably T is methyl or butyl radical; T¹ is an halogen        atom or a group OR″ wherein R″ is a linear or branched,        saturated or unsaturated C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl,        C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radical,        optionally containing one or more heteroatoms belonging to        groups 13–17 of the Periodic Table of the Elements; preferably        T¹ is an halogen atom, more preferably bromine; wherein the        molar ratio between said base and the ligand of the        formula (III) and is at least 2:1; excess of said base can be        used; and-   b) contacting the product obtained in step a) with a compound of    formula MX₄ wherein M and X have the meaning described above.

The process is preferably carried out in an aprotic solvent, eitherpolar or apolar. Said aprotic solvent is preferably an aromatic oraliphatic hydrocarbon, optionally halogenated, or an ether; morepreferably it is selected from benzene, toluene, pentane, hexane,heptane, cyclohexane, dichloromethane, diethylether, tetrahydrofuraneand mixtures thereof. The above process is carried out at a temperatureranging from −100° C. to +80° C., more preferably from −20° C. to +70°C.

The ligands of formula (III) can be obtained with a process comprisingthe following steps:

-   a) contacting a compound of formula (IVa):

-    and/or its double bond isomer    -   wherein R¹, R², R³, R⁴, R⁵ and R⁶ are defined as above;    -   with a base selected from T_(j)B, TMgT¹, sodium and potassium        hydride, metallic sodium and potassium; wherein T, j, B and T¹        are defined as above, and wherein the molar ratio between said        base and the compound of the formula (IVa) is at least 1:1;        excess of said base can be used;-   b) contacting the anionic compound obtained in step a) with a    compound of formula (IVb):

-    wherein R¹, R², R³, R⁴, R⁵, R⁶ and L are defined as above and Y is    chlorine, bromine and iodine, preferably Y is chlorine or bromine.

When the indenyl moieties are the same, i.e. the substituents R¹, R²,R³, R⁴, R⁵ and R⁶ are the same on both the indenyl moieties, analternative process for preparing the ligand of formula (III) comprisesthe following steps:

-   a) contacting a compound of formula (IVa):

-    and/or its double bond isomer    -   wherein R¹, R², R³, R⁴, R⁵ and R⁶ are defined as above; with a        base selected from T_(j)B, TMgT¹, sodium and potassium hydride,        metallic sodium and potassium; wherein T, j, B, and T¹ are        defined as above, and wherein the molar ratio between said base        and the compound of the formula (IVa) is at least 1:1, excess of        said base can be used;-   b) reacting the product obtained in step a) with a compound of    formula YLY, wherein L and Y are defined as above, wherein the molar    ratio between the compound obtained in step a) and the compound of    formula YLY is at least 2:1; excess of the compound obtained    instep a) can be used.

Alumoxanes used as component b) can be obtained by reacting water withan organo-aluminium compound of formula H_(j)AlU_(3−j) orH_(j)Al₂U_(6−j), where the U substituents, same or different, arehydrogen atoms, halogen atoms, C₁–C₂₀-alkyl, C₃–C₂₀-cyclalkyl,C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionallycontaining silicon or germanium atoms, with the proviso that at leastone U is different from halogen, and j ranges from 0 to 1, being also anon-integer number. In this reaction the molar ratio of Al/water ispreferably comprised between 1:1 and 100:1.

The molar ratio between aluminium and the metal of the metallocene isgenerally comprised between about 10:1 and about 30000:1, preferablybetween about 100:1 and about 5000:1.

The alumoxanes used in the catalyst according to the invention areconsidered to be linear, branched or cyclic compounds containing atleast one group of the type:

wherein the substituents U, same or different, are defined above.

In particular, alumoxanes of the formula:

can be used in the case of linear compounds, wherein n¹ is 0 or aninteger of from 1 to 40 and the substituents U are defined as above; oralumoxanes of the formula:

can be used in the case of cyclic compounds, wherein n² is an integerfrom 2 to 40 and the U substituents are defined as above.

Examples of alumoxanes suitable for use according to the presentinvention are methylalumoxane (MAO), tetra-(isobutyl)alumoxane (TIBAO),tetra-(2,4,4-trimethyl-pentyl)alumoxane (TIOAO),tetra-(2,3-dimethylbutyl)alumoxane (TDMBAO) andtetra-(2,3,3-trimethylbutyl)alumoxane (TTMBAO).

Particularly interesting cocatalysts are those described in WO 99/21899and in WO01/21674 in which the alkyl and aryl groups have specificbranched patterns.

Non-limiting examples of aluminium compounds that can be reacted withwater to give suitable alumoxanes (b), described in WO 99/21899 andWO01/21674, are: tris(2,3,3-trimethyl-butyl)aluminium,tris(2,3-dimethyl-hexyl)aluminium, tris(2,3-dimethyl-butyl)aluminium,tris(2,3-dimethyl-pentyl)aluminium, tris(2,3-dimethyl-heptyl)aluminium,tris(2-methyl-3-ethyl-pentyl)aluminium,tris(2-methyl-3-ethyl-hexyl)aluminium,tris(2-methyl-3-ethyl-heptyl)aluminium,tris(2-methyl-3-propyl-hexyl)aluminium,tris(2-ethyl-3-methyl-butyl)aluminium,tris(2-ethyl-3-methyl-pentyl)aluminium,tris(2,3-diethyl-pentyl)aluminium,tris(2-propyl-3-methyl-butyl)aluminium,tris(2-isopropyl-3-methyl-butyl)aluminium,tris(2-isobutyl-3-methyl-pentyl)aluminium,tris(2,3,3-trimethyl-pentyl)aluminium,tris(2,3,3-trimethyl-hexyl)aluminium,tris(2-ethyl-3,3-dimethyl-butyl)aluminium,tris(2-ethyl-3,3-dimethyl-pentyl)aluminium,tris(2-isopropyl-3,3-dimethyl-butyl)aluminium,tris(2-trimethylsilyl-propyl)aluminium,tris(2-methyl-3-phenyl-butyl)aluminium,tris(2-ethyl-3-phenyl-butyl)aluminium,tris(2,3-dimethyl-3-phenyl-butyl)aluminium,tris(2-phenyl-propyl)aluminium,tris[2-(4-fluoro-phenyl)-propyl]aluminium,tris[2-(4-chloro-phenyl)-propyl]aluminium,tris[2-(3-isopropyl-phenyl)-propyl]aluminium,tris(2-phenyl-butyl)aluminium, tris(3-methyl-2-phenyl-butyl)aluminium,tris(2-phenyl-pentyl)aluminium,tris[2-(pentafluorophenyl)-propyl]aluminium,tris[2,2-diphenyl-ethyl]aluminium andtris[2-phenyl-2-methyl-propyl]aluminium, as well as the correspondingcompounds wherein one of the hydrocarbyl groups is replaced with ahydrogen atom, and those wherein one or two of the hydrocarbyl groupsare replaced with an isobutyl group.

Amongst the above aluminium compounds, trimethylaluminium (TMA),triisobutylaluminium (TIBA), tris(2,4,4-trimethyl-pentyl)aluminium(TIOA), tris(2,3-dimethylbutyl)aluminium (TDMBA) andtris(2,3,3-trimethylbutyl)aluminium (TTMBA) are preferred.

Non-limiting examples of compounds able to form an alkylmetallocenecation are compounds of formula D⁺E⁻, wherein D⁺ is a Brønsted acid,able to donate a proton and to react irreversibly with a substituent Xof the metallocene of formula (I) and E⁻ is a compatible anion, which isable to stabilize the active catalytic species originating from thereaction of the two compounds, and which is sufficiently labile to beremoved by an olefinic monomer. Preferably, the anion E⁻ comprises oneor more boron atoms. More preferably, the anion E⁻ is an anion of theformula BAr₄ ⁽⁻⁾, wherein the substituents Ar which can be identical ordifferent are aryl radicals such as phenyl, pentafluorophenyl orbis(trifluoromethyl)phenyl. Tetralis-pentafluorophenyl borate isparticularly preferred compound, as described in WO 91/02012. Moreover,compounds of formula BAr₃ can be conveniently used. Compounds of thistype are described, for example, in the International patent applicationWO 92/00333. Other examples of compounds able to form analkylmetallocene cation are compounds of formula BAr₃P wherein P is asubstituted or unsubstituted pyrrol radical. These compounds aredescribed in WO01/62764. Compounds containing boron atoms can beconveniently supported according to the description of DE-A-19962814 andDE-A-19962910. All these compounds containing boron atoms can be used ina molar ratio between boron and the metal of the metallocene comprisedbetween about 1:1 and about 10:1; preferably 1:1 and 2.1; morepreferably about 1:1.

Non limiting examples of compounds of formula D⁺E⁻ are:

-   Triethylammoniumtetra(phenyl)borate,-   Tributylammoniumtetra(phenyl)borate,-   Trimethylammoniumtetra(tolyl)borate,-   Tributylammoniumtetra(tolyl)borate,-   Tributylammoniumtetra(pentafluorophenyl)borate,-   Tributylammoniumtetra(pentafluorophenyl)aluminate,-   Tripropylammoniumtetra(dimethylphenyl)borate,-   Tributylammoniumtetra(trifluoromethylphenyl)borate,-   Tributylammoniumtetra(4-fluorophenyl)borate,-   N,N-Dimethylbenzylammonium-tetrakispentafluorophenylborate,-   N,N-Dimethylhexylamonium-tetrakispentafluorophenylborate,-   N,N-Dimethylaniliniumtetra(phenyl)borate,-   N,N-Diethylaniliniumtetra(phenyl)borate,-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)borate,-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)aluminate,-   N,N-Dimethylbenzylammonium-tetrakispentafluorophenylborate,-   N,N-Dimethylhexylamonium-tetrakispentafluorophenylborate,-   Di(propyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Di(cyclohexyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Triphenylphosphoniumtetrakis(phenyl)borate,-   Triethylphosphoniumtetrakis(phenyl)borate,-   Diphenylphosphoniumtetrakis(phenyl)borate,-   Tri(methylphenyl)phosphoniumtetrakis(phenyl)borate,-   Tri(dimethylphenyl)phosphoniumtetrakis(phenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)aluminate,-   Triphenylcarbeniumtetrakis(phenyl)aluminate,-   Ferroceniumtetrakis(pentafluorophenyl)borate,-   Ferroceniumtetrakis(pentafluorophenyl)aluminate.-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate, and-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)borate.

Organic aluminum compounds used as compound c) are those of formulaH_(j)AlU_(3−j) or H_(j)Al₂U_(6−j) as described above.

The polymerization process of the present invention can be carried outin liquid phase. The polymerization medium can be 1-butene optionally inthe presence of an inert hydrocarbon solvent. Said hydrocarbon solventcan be either aromatic (such as toluene) or aliphatic (such as propane,hexane, heptane, isobutane, cyclohexane and 2,2,4-trimethylpentane).Otherwise the polymerization process of the present invention can becarried out in a gas phase. Preferably the polymerization is carried outby using liquid 1-butene i.e. the monomer, as the polymerization medium(bulk polymerization).

The catalyst system of the present invention can also be supported on aninert carrier. This is achieved by depositing the metallocene compounda) or the product of the reaction thereof with the component b), or thecomponent b) and then the metallocene compound a) on an inert supportsuch as, for example, silica, alumina, Al—Si, Al—Mg mixed oxides,magnesium halides, styrene/divinylbenzene copolymers, polyethylene orpolypropylene. The supportation process is carried out in an inertsolvent, such as hydrocarbon selected from toluene, hexane, pentane andpropane and at a temperature ranging from 0° C. to 100° C., more from30° C. to 60° C.

A particularly suitable process for supporting the catalyst system isdescribed in WO01/44319, wherein the process comprises the steps of:

-   (a) preparing a catalyst solution comprising a soluble catalyst    component;-   (b) introducing into a contacting vessel:    -   (i) a porous support material in particle form, and    -   (ii) a volume of the catalyst solution not greater than the        total pore volume of the porous support material introduced;-   (c) discharging the material resulting from step (b) from the    contacting vessel and suspending it in an inert gas flow, under such    conditions that the solvent evaporates; and-   (d) reintroducing at least part of the material resulting from    step (c) into the contacting vessel together with another volume of    the catalyst solution not greater than the total pore volume of the    reintroduced material.

A suitable class of supports comprises porous organic supportsfunctionalized with groups having active hydrogen atoms. Particularlysuitable are those in which the organic support is a partiallycrosslinked styrene polymer. Supports of this type are described in EP633 272.

Another class of inert supports particularly suitable for use accordingto the invention is that of polyolefin porous prepolymers, particularlypolyethylene.

A further suitable class of inert supports for use according to theinvention is that of porous magnesium halides, such as those describedin WO 95/32995.

The polymerization temperature preferably ranges from 0° C. to 250° C.;preferably comprised between 20° C. and 150° C. and, more particularlybetween 40° C. and 90° C.

Generally, the polymers of the present invention are endowed with anarrow molecular weight distribution M_(w)/M_(n), when the metalloceneused is a pure isomer, M_(w)/M_(n) is preferably lower than 3, morepreferably lower than 2.5.

The molecular weight distribution can be varied by using mixtures ofdifferent metallocene compounds or mixtures of the metallocene compoundof formula (I) and a Ziegler-Natta catalyst or by carrying out thepolymerization in several stages at different polymerizationtemperatures and/or different concentrations of the molecular weightregulators and/or different monomer concentration.

The polymerization yield depends on the purity of the transition metalorganometallic catalyst compound (the metallocene compound of formula(I)) a) in the catalyst, therefore, said compound can be used as such orcan be subjected to purification treatments before use. With the processof the present invention 1-butene can be homopolymerized with highyields and the isotactic polymers obtained show a high molecular weightand a relatively low melting point. The obtained polymer is endowed withimproved flexibility and elongation at break.

When 1-butene is copolymerized with ethylene, propylene or an alphaolefin of formula CH₂═CHZ wherein Z is a C₃–C₁₀ alkyl group a copolymerhaving a comonomer derived unit content up to 30% by mol can beobtained. Preferably the comonomer content ranges from 0.5 to 20% bymol. Preferred comonomers are ethylene, propylene or 1-hexene.

A further object of the present invention is a metallocene compound offormula (IIb):

wherein M, p, L, R¹, R², R³, R⁶, R⁷and X have the meaning describedabove.

The metallocene compounds of formula (IIb) can be prepared according tothe process described above starting from the ligand of formula (V) orits corresponding double bond isomers:

wherein L, R¹, R², R³, R⁶, and R⁷ are described above; preferably R¹ isa C₁–C₂₀-alkyl radical; more preferably it is a methyl or ethyl radical;R², R³ and R⁶ are preferably hydrogen atoms; preferably R⁷ is a linearor branched, saturated or unsaturated C₁–C₂₀-alkyl radical; morepreferably it is a methyl or ethyl radical; preferably L is Si(R⁸)₂wherein R⁸ is a linear or branched, saturated or unsaturatedC₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl orC₇–C₂₀-arylalkyl radical; more preferably L is Si(CH₃)₂ or SiPh₂.Instead of using the ligand of formula (III)

Thus it is a further object of the present invention a process forpreparing the metallocene compounds of formula (IIb) comprising thefollowing steps:

-   a) contacting a ligand of formula (V)

-    and/or its double bond isomer    -   wherein: R¹, R², R³, R⁵, R⁶, R⁷ and L are described above with a        base of formula T_(j)B or TMgT¹, or sodium or potassium hydride,        or metallic sodium or potassium; wherein B is an alkaline or        alkali-earth metal; and j is 1 or 2, j being equal to 1 when B        is an alkaline metal, and j being equal to 2 when B is an        alkali-earth metal; T is selected from the group consisting of        linear or branched, saturated or unsaturated C₁–C₂₀ alkyl,        C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alklaryl or C₇–C₂₀        arylalkyl groups, optionally containing one or more Si or Ge        atoms; T¹ is an halogen atom or a group OR″ wherein R″ is a        linear or branched, saturated or unsaturated C₁–C₂₀-alkyl,        C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or        C₇–C₂₀-arylalkyl radicals, optionally containing one or more        heteroatoms belonging to groups 13–17 of the Periodic Table of        the Elements; wherein the molar ratio between said base and the        ligand of the formula (V) is at least 2:1; excess of said base        can be used; and-   b) contacting the product obtained in step a) with a compound of    formula MX₄ wherein M and X have been described above.

The compound of formula (V) can be prepared starting from the compoundsof formula (VI) and (VII)

according to the processes described above by using the compounds offormulas (VI) and (VII) instead of the compound of formulas (IVa) and(IVb).

Thus it is a further object of the present invention is a process forpreparing the ligand of formula (V) comprising the following steps:

-   a) contacting a compound of formula (VI):

-    or its double bonds isomer    -   wherein: R¹, R², R³, R₆, and R⁷ are described above;    -   with a base of formula T_(j)B or TMgT¹, or sodium or potassium        hydride, or metallic sodium or potassium; wherein T, j, B, and        T¹ are described above, wherein the molar ratio of said base and        the compound of the formula (VI) is at least 1:1; excess of said        base can be used;-   b) contacting the anionic compounds obtained in step a) with a    compound of formula (VII):

-    or its double bonds isomer    -   wherein R¹, R², R³, R⁶, R⁷ and L are described above and Y is a        halogen radical selected from the group consisting of chloride,        bromide and iodide.

When the substituents R¹, R², R³, R⁴, R⁵ and R⁶ are the same in both theindenyl moieties an alternative process for preparing the ligand offormula (V) comprises the following steps:

-   a) contacting a compound of formula (VI):

-    or its double bonds isomer    -   wherein: R¹, R², R³, R⁶, R⁷ and L are described above; with a        base of formula T_(j)B or TMgT¹, or sodium or potassium hydride,        or metallic sodium or potassium; wherein T, j, B, and T¹ are        described above, wherein the molar ratio between said base and        the compound of the formula (VI) is at least 1:1; excess of said        base can be used; and-   b) reacting the product obtained in step a) with a compound of    formula YLY, wherein L and Y are described above wherein the molar    ratio between the compound obtained in step a) and the compound of    formula YLY is at least 2:1; excess of compound obtained in step a)    can be used.

The following examples are given for illustrative purpose and do notintend to limit the invention.

EXAMPLES

General Procedures

All operations were performed under nitrogen by using conventionalShlenk-line techniques. Solvents were purified by degassing withnitrogen and passing over activated Al₂O₃ and stored under nitrogen. Allcompounds were analyzed by ¹H-NMR and ¹³C-NMR on a DPX 200 Brukerspectrometer (CDCl₃, referenced against the peak of residual CHCl₃ at7.25 ppm). Due to the low solubility of the Zirconocene, the ¹³C-NMRspectra of this compound were performed on a Bruker DPX 400 in CD₂Cl₄ at120° C.

Example 1 Synthesis ofMe₂Si[2-Me-5,6(tetramethylcyclotrymethylen)indenyl]₂ZrCl₂[A1] Synthesisof 1,1,3,3-Tetramethylindane

A mixture of 117.26 g of α-Methylstyrene (Aldrich 99%, 0.98 mol) and73.0 g of t-Butanol (Aldrich 99%, 0.97 mol) were slowly added (1 hour)to a mixture of 200 g of acetic acid and 200 g of sulfuric acid,previously warmed at 40° C. The suspension so-obtained was stirred 30min at 40° C. and then the 2 layers were separated. The organic layerwas washed with a 0.7 M NaOH acqueous solution (3×50 ml, neutrality) andwater (2×50 ml). The opaque yellow solution obtained was then distilledat 26 mbar. At about 100° C. a colourless transparent liquid wasdistilled off (28.43 g), which was characterized by NMR as pure 1,1,3,3tetramethylindane (16.6% yield).

¹H-NMR (CDCl₃, δ, ppm): 1.39 (s, CH₃, H8 and H9, 12H); 1.99 (s, CH₂, H2,2H); 7.17–7.30 (m, Ar, H4, H5, H6 and H7, 4H). ¹³C-NMR (CDCl₃, δ, ppm):31.56 (CH₃, C8 and C9, 4C); 42.51 (C, C1 and C3, 2C); 56.60 (CH₂, C2,1C) ; 122.45 and 126.69 (Ar, C4, C5, C6 and C7, 4C); 151.15 (Ar, C3a andC7a, 2C).

Synthesis of 2,5,5,7,7-Pentamethyl-2,3,5,6,7-pentahydro-s-indacen-1-one

50.71 g of AlCl₃ (Aldrich 99%, 376.5 mmol) were slowly added (30 min) toa mixture of 28.43 g of 1,1,3,3 tetramethylindane (163.1 mmol), 38.32 gof 2-Bromoisobutyryl bromide (Aldrich 98%, 163.3 mmmol) and 500 ml ofCH₂Cl₂ at 0° C. The solution colour turned yellow and finally dark red.The suspension was stirred 17 hours at room temperature and thenquenched with 200 g of ice. The green organic layer was washed with a 1M HCl acqueous solution (1×200 ml), a saturated NaHCO₃ solution (2×200ml) and water (2×200 ml). Then it was dried over Na₂SO₄, filtered andevaporated to dryness under reduced pressure to give 38.23 g (96.7%yield) of a green solid. This solid was determined by GC-MS to contain76.7% of the desired product. This was treated with 50 ml of MeOH andfiltered. The white residue was washed with MeOH and dried to obtain20.28 g of a white powder. The filtrate was stored at −20° C., to obtain3.95 g of a white powder, collected with the previous one. This powderwas characterized by NMR as pure2,5,5,7,7-Pentamethyl-2,3,5,6,7-pentahydro-s-indacen-1-one. The yield onthe isolated pure product was 61.3%.

¹H-NMR (CDCl₃, δ, ppm): 1.27 (s, CH₃, H9, 3H); 1.31 (s, CH₃, H11, 6H);1.33 (s, CH₃, H10, 6H); 1.95 (s, CH₂, H6, 2H),; 2.62-2.79 (m, CH₂ andCH, H2 and H3, 2H); 3.28–3.37 (m, CH₂, H3, 1H); 7.15 (s, Ar, H4, 1H);7.51 (s, Ar, H8, 1H). ¹³C-NMR (CDCl₃, δ, ppm): 16.34 (CH₃, C9, 1C);31.28, 31.30 (CH₃, C10, 2C); 31.50, 31.55 (CH₃, C11, 2C); 34.73 (CH₂,C3, 1C); 41.86 (C, C7, 1C); 42.38 (CH, C2, 1C); 42.52 (C, C5, 1C); 56.44(CH₂, C6, 1C); 117.87 (Ar, C8, 1C); 120.22 (Ar, C4, 1C); 135.67 (Ar,C8a, 1C); 151.69 (Ar, C7a, 1C); 152.91 (Ar, C₃a, 1C); 159.99 (Ar, C4a,1C); 208.96 (C═O, C1, 1C).

Synthesis of 2,5,5,7,7-Pentamethyl-1,2,3,5,6,7-hexahydro-s-indacen-1-ol

A suspension of 2.70 g of pure2,5,5,7,7-Pentamethyl-2,3,5,6,7-pentahydro-s-indacen-1-one (11.1 mmol)in 15 ml of Ethanol was treated with 0.46 g of NaBH₄ (Aldrich 98%, 11.9mmol) at room temperature. An opaque yellowish solution was obtained.After 18 hours stirring at room temperature, the solution was treatedwith 2 ml of acetone and then evaporated to dryness under reducedpressure. The yellowish gel obtained was treated with 35 ml of tolueneand 35 ml of water. The two layers were separated. The acqueous layerwas washed with 20 ml of toluene. The organic layer was washed with a10% NH₄Cl acqueous solution (2×20 ml), dried over Na₂SO₄ and filtered.The filtrate was evaporated to dryness under reduced pressure to give2.54 g of a white powder (93.7% yield), which was characterized by NMRas pure 2,5,5,7,7-Pentamethyl-1,2,3,5,6,7-hexahydro-s-indacen-1-ol.Owing to the presence of 2 chiral centers (carbons C1 and C2), thissample is characterized by the presence of 2 isomers: indicated with Aand B. The A:B ratio observed by ¹H-NMR spectrum was 60:40.

¹H-NMR (CDCl₃, δ, ppm): 1.17 (d, CH₃, H9, 3H, J=6.85, isomer B); 1.27(d, CH₃, H9, 3H, J=6.85, isomer A); 1.31 (s, CH₃, H10 and H11, 12H,isomer A and B); 1.48 (d, OH, 1H, J=6.85, isomer A); 1.80 (d, OH, 1H,J=6.85, isomer B); 1.93 (s, CH₂, H6, 2H, isomer A and B); 2.17–3.13 (m,CH and CH₂, H2 and H3, 3H, isomer A and B); 4.69 (t, CH, H1, 1H, J=7.24,isomer A); 4.95 (t, CH, H1, 1H, J=8.57, isomer B); 6.95 (s, Ar, H4, 1H,isomer A); 6.97 (s, Ar, H4, 1H, isomer B); 7.14 (s, Ar, H8, 1H, isomerA); 7.17 (s, Ar, H8, 1H, isomer B). ¹³C-NMR (CDCl₃, δ, ppm): 13.88 (CH₃,C9, 1C, isomer B); 17.87 (CH₃, C9, 1C, isomer A); 31.58, 31.65, 31.69,31.75 (CH₃, C10 and C11, 4C, isomer A and B); 37.64–37.75 (CH₂, C3, 1C);39.62 (CH, C2, 1C, isomer B); 42.11–42.16 (C, C5 and C7, 2C, isomer Aand B); 45.99 (CH, C2, 1C, isomer A); 56.89 (CH₂, C6, 1C); 77.51 (C—OH,C1, 1C, isomer B); 82.78 (C—OH, C1, 1C, isomer A); 117.80, 118.62,118.80 (Ar, C4 and C8, 2C, isomer A and B); 140.68–152.10 (Ar, C₃a, C4a,C7a, C8a).

Synthesis of 1,1,3,3,6-Pentamethyl-1,2,3,5-tetrahydro-s-indacene

A suspension of 24.36 g of pure2,5,5,7,7-Pentamethyl-2,3,5,6,7-pentahydro-s-indacen-1-one (100.5 mmol)in 100 ml of Ethanol was treated with 4.06 g of NaBH₄ (Aldrich 98%,105.2 mmol) at room temperature. An opaque yellowish solution wasobtained. After 4 hours stirring at room temperature, the solution wastreated with 5 ml of acetone and then evaporated to dryness underreduced pressure. The yellowish gel obtained was treated with 100 ml oftoluene and 40 ml of water. The two layers were separated. The acqueouslayer was washed with 50 ml of toluene. The organic layer was washedwith a 10% NH₄Cl acqueous solution (2×30 ml), dried over Na₂SO₄ andfiltered. The yellow filtrate was treated with 1.89 g ofp-Toluenesulfonic acid monohydrate (Aldrich 98.5%, 9.8 mmol) and heatedto 80° C. Formation of water with the separation of 2 layers wasobserved. After 5 hours stirring at 80° C. and 2 days at roomtemperature, the reaction was not finished (11% of alcohol), so thewater formed was separated from the reaction mixture and 0.20 g ofp-Toluenesulfonic acid monohydrate (Aldrich 98.5%, 1,0 mmol) were added.After 1 hour stirring at 80° C. and 16 hours at room temperature, thereaction was complete and so the mixture was treated with 50 ml of asaturated NaHCO₃ acqueous solution. The organic layer was separated,washed with a saturated NaHCO₃ acqueous solution (1×50 ml) and water(3×50 ml), dried over Na₂SO₄ and filtered. The yellow filtrate wasevaporated to dryness under reduced pressure to give 20.89 g of a yellowliquid (91.8% yield), that crystallized after few minutes. This wascharacterized by NMR as pure1,1,3,3,6-Pentamethyl-1,2,3,5-tetrahydro-s-indacene.

¹H-NMR (CDCl₃, δ, ppm): 1.38 (s, CH₃, H9 e H10, 12H); 2.00 (s, CH₂, H2,2H); 2.18 (bs, CH₃, H11, 3H); 3.30 (s, CH₂, H5, 2H); 6.51 (s, CH, H7,1H); 7.06 (s, Ar, H8, 1H); 7.18 (s, Ar, H4, 11H). ¹³C-NMR (CDCl₃, δ,ppm): 16.81 (CH₃, C11, 1C); 31.77 (CH₃, C9 e C10, 4C); 42.08, 42.16 (C,C1 e C3, 2C); 42.28 (CH₂, C5, 1C); 57.04 (CH₂, C2, 1C); 113.61 (Ar, C8,1C); 117.55 (Ar, C4, 1C); 127.13 (CH, C7, 1C); 142.28 (Ar, C4a, 1C);145.00, 145.26 (Ar and C═, C7a and C6, 2C); 146.88 (Ar, C₃a, 1C); 149.47(Ar, C8a, 1C).

dimethyl-bis-(2,5,5,7,7-pentamethyl-1,5,6,7-tetrahydro-s-indacen-1-yl)-silane

8.8 ml of a 2.5 M BuLi diethyl ether solution (Aldrich, 22.0 mmol) wereslowly added to a solution of 4.99 g of1,1,3,3,6-Pentamethyl-1,2,3,5-tetrahydro-s-indacene (22.0 mmol) in 65 mlof diethyl ether at 0° C. The yellow suspension formed was then stirredat room temperature. ¹H-NMR showed the complete formation of the lithiumsalt after 1 hour. So a solution of 1.51 g of Dimethyldichloro silane(Fluka 99%, 11.6 mmol) in 30 ml of THF was added to the reaction mixtureat 0° C. The clear yellow suspension was then stirred at roomtemperature for 20 hours. Then the suspension was evaporated to drynessunder reduced pressure, to give a yellow sticky solid. This was treatedwith 70 ml of toluene and filtered. The white residue on the frit waswashed twice with 20 ml of toluene. The yellow filtrate was evaporatedto dryness under reduced pressure, to give 5.67 g of a yellow stickysolid, containing the desired product (rac:meso=20:80), some startingindene (11% respect to the product) and some other unkown products. Thissolid was treated with 20 ml of pentane to form a pale yellow solutionwith a white precipitate, which was filtered and dried. 0.53 g of awhite powder were obtained, which was characterized by NMR as purerac-dimethyl-bis-(2,5,5,7,7-pentamethyl-1,5,6,7-tetrahydro-s-indacen-1-yl)-silane.The filtrate was concentrated to 10 ml and cooled at −20° C. After 20hours a white solid (2.27 g g) was separated from the solution, whichwas characterized by NMR as puredimethyl-bis-(2,5,5,7,7-pentamethyl-1,5,6,7-tetrahydro-s-indacen-1-yl)-silane(rac:meso=10:90). Other 1.12 g of pure product were then crystallized.Total yield on the pure isolated product was 57.0%.

Rac isomer

¹H-NMR (CDCl₃, δ, ppm): −0.23 (s, Si—CH₃, 6H); 1.32 (s, CH₃, H11, 12H);1.37, 1.38 (s, CH₃, H10, 12H); 1.97 (s, CH₂, H6, 4H); 2.19 (bs, CH₃, H9,6H); 3.62 (s, CH, H1, 2H); 6.58 (s, CH, H3, 2H); 7.10 (s, Ar, H4, 2H);7.27 (s, Ar, H8, 2H). ¹³C-NMR (CDCl₃, δ, ppm): −5.52 (Si—CH₃, 2C); 17.90(CH₃, C9, 2C); 31.68, 31.80, 31.98 (CH₃, C10 e C11, 8C); 42.06, 42.13(C, C5 e C7, 4C); 46.69 (CH, C1, 2C); 57.13 (CH₂, C6, 2C); 113.60 (Ar,C4, 2C); 117.15 (Ar, C8, 2C); 126.69 (CH, C3, 2C); 143.78 (Ar, C8a, 2C);144.40 (Ar, C3a, 2C); 146.19 (C═, C2, 2C); 146.35 (Ar, C7a, 2C); 148.63(Ar, C4a, 2C).

Meso isomer

¹H-NMR (CDCl₃, δ, ppm): −0.29, −0.16 (s, Si—CH₃, 6H); 1.28, 1.30 (s,CH₃, H11, 12H); 1.32, 1.33 (s, CH₃, H10, 12H); 1.93 (s, CH₂, H6, 4H);2.16 (bs, CH₃, H9, 6H); 3.51 (s, CH, H1, 2H); 6.57 (s, CH, H3, 2H); 7.06(s, Ar, H4, 2H); 7.08 (s, Ar, H8, 2H). ¹³C-NMR (CDCl₃, δ, ppm): −5.04,−4.67 (Si—CH₃, 2C); 17.83 (CH₃, C9, 2C), 31.70, 31.79, 31.96 (CH₃, C10 eC11, 8C); 42.05, 42.12 (C, C5 e C7, 4C); 46.55 (CH, C1, 2C); 57.10 (CH₂,C6, 2C); 113.59 (Ar, C4, 2C); 117.29 (Ar, C8, 2C); 126.59 (CH,C_(3, 2)C); 143.88 (Ar, C8a, 2C); 144.27 (Ar, C3a, 2C); 146.33 (C═, C2,2C); 146.53 (Ar, C7a, 2C); 148.62 (Ar, C4a, 2C).

Synthesis ofMe₂Si[2-Me-5,6(tetramethylcyclotrimethylen)indenyl]₂ZrCl₂|A1|

1.39 ml of a 1.5 M MeLi diethyl ether solution (Aldrich, 2.1 mmol) wereslowly added to a suspension of 0.53 g of purerac-dimethyl-bis-(2,5,5,7,7-pentamethyl-1,5,6,7-tetrahydro-s-indacen-1-yl)-silane(1.0 mmol) in 10 ml of diethyl ether at 0° C. After 90 min stirring atroom temperature, the pale yellow suspension was added to a suspensionof 0.25 g of ZrCl₄ (Aldrich, 1.1 mmol) in 10 ml of Pentane at 0° C. Ayellow suspension was formed. After 20 hours stirring at roomtemperature ¹H-NMR analysis showed the formation of the desired product(rac:meso=95:5,). The rac isomer was used for the polymerization tests.

Rac isomer

¹H-NMR (CDCl₃, δ, ppm): 1.22, 1.31 (s, CH₃, H11, 12H); 1.28 (s, Si—CH₃,6H); 1.33, 1.42 (s, CH₃, H10, 12H); 1.90 (d, CH₂, H6, 4H, J=0.78); 2.19(s, CH₃, H9, 6H); 6.70 (s, CH, H3, 2H); 7.22 (s, Ar, H4, 2H, J=0.78);7.28 (s, Ar, H8, 2H, J=0.78). ¹³C-NMR (CD₂Cl₄, δ, ppm): 2.86 (Si—CH₃,2C); 18.39 (CH₃, C9, 2C); 31.41 (CH₃, C11, 2C); 31.63, 31.64 (CH₃, C10 eC11, 4C); 33.43 (CH₃, C10, 2C); 41.72, 41.75 (C, C5 e C7, 4C); 57.50(CH₂, C6, 2C); 81.77 (Ar, C1, 2C); 117.77 (Ar, C8, 2C); 118.40 (Ar, C4,2C); 121.37 (Ar, C3, 2C); 127.21 (Ar, C8a, 2C); 133.44 (Ar, C3a, 2C);134.64 (Ar, C2, 2C); 152.15 (Ar, C7a, 2C); 155.45 (Ar, C4a, 2C).

Example 2 Alternative Route for the Synthesis ofMe₂Si[2-Me-5,6(tetramethylcyclotrymethylen)indenyl]₂ZrCl₂[A1]

5.0 ml of a 2.5 M BuLi solution (Aldrich, 12.6 mmol) were slowly addedto a suspension of 3.2 g of puredimethyl-bis-(2,5,5,7,7-pentamethyl-1,5,6,7-tetrahydro-s-indacen-1-yl)-silane(experiment 20826/93, MW=508.86, 6.3 mmol) in 40 ml of ether at 0° C.After 3 hours stirring at room temperature, the pale yellow suspensionwas added to a suspension of 1.50 g of ZrCl₄ in 40 ml of Pentane at 0°C. A yellow-orange suspension was formed. After 18 hours stirring atroom temperature ¹H-NMR analysis showed the formation of the desiredproduct (rac:meso=60:40,), so the suspension was filtered. The yellowresidue (3.6 g) was treated on the frit with toluene (≈300 ml). Thefiltrate was evaporated to dryness under reduced pressure to give 2.41 gof a yellow powder containingMe₂Si[2-Me-5,6(tetramethyltrimethylen)indenyl]₂ZrCl₂ (rac:meso=61:39).The pale yellow residue on the frit was treated with 50 ml of tolueneand filtered. 160 mg of purerac-Me₂Si[2-Me-5,6(tetramethyltrimethylen)indenyl]₂ZrCl₂ were obtainedfrom the filtrate. The total yield was 61.2%. The rac isomer was usedfor the polymerization tests.

Polymerization Examples

General Procedures

The intrinsic viscosity (I.V.) was measured in tetrahydronaphtalene(THN) at 135° C.

The molecular weight and the molecular weight distribution weredetermined on a WATERS 150 C using the following chromatographicconditions:

Columns: 3x SHODEX AT 806 MS; 1x SHODEX UT 807; 1x SHODEX AT-G; Solvent:1,2,4 trichlorobenzene (+0.025% 2,6-Di-tert.Butyl-4- Methyl-Phenol);Flow rate: 0.6–1 ml/min; Temperature: 135° C.; Detector: INFRARED AT λ ≅3.5 μm; Calibration: Universal Calibration with PS-Standards.

The melting points of the polymers (T_(m)) were measured by DifferentialScanning Calorimetry (D.S.C.) on a Perkin Elmer DSC-7 instrument,according to the standard method. A weighted sample (5–10 mg) obtainedfrom the polymerization was sealed into aluminum pans and heated to 180°C. at 10° C./minute. The sample was kept at 180° C. for 5 minutes toallow a complete melting of all the crystallites, then cooled to 20° C.at 10° C./minute. After standing 2 minutes at 20° C., the sample washeated for the second time at 180° C. with a scanning speedcorresponding to 10° C./min. In this second heating run, the peaktemperature was taken as the melting temperature (T_(m)) and the area ofthe peak as melting enthalpy (ΔH_(f)).

Rac dimethylsilylbis(2-methyl-4-phenyl-indenyl) zirconium dichloride[A-2] was prepared according to U.S. Pat. No. 5,786,432. Racdimethylsilylbis(2-methyl-4,5benzo-indenyl)zirconium dichloride [A-3]was prepared according to U.S. Pat. No. 5,830,821.

Polymerization Examples 1–3 and Comparative Examples 4–5 1-butenehomopolymerization

The catalyst mixture was prepared by dissolving the metallocene with theproper amount of the MAO solution in toluene (Al/Zr ratio reported intable 1), obtaining a solution which was stirred for 10 min at roomtemperature before being injected into the autoclave. A 4.25 litressteel autoclave, equipped with magnetically stirred anchor (stirringrate 550 rpm) and with a Flow Record & Control system (FRC) havingmaximum flow rate of 9000 g/hour for 1-butene, was purged with warmnitrogen (1.5 barg N₂, 700° C., 1 hour). 1-Butene was fed into thereactor (1350 g at 30° C.) together with 6 mmol of Al(i-Bu)₃ (TIBA) (asa 1 M solution in hexane), and stirring was started. Subsequently, thereactor inner temperature was raised from 30° C. to the polymerisationtemperature (indicated in table 1). When pressure and temperature wereconstant, the catalytic solution was fed into the reactor with anitrogen overpressure. The polymerisation was run for the time indicatedin table 1 at the chosen polymerization temperature. Then the stirringwas interrupted; the pressure into the autoclave was raised to 20 bar-gwith nitrogen. The bottom discharge valve was opened and the1-butene/poly-1-butene mixture was discharged into a heated steel tankcontaining water at 70° C. The tank heating was switched off and a flowof nitrogen at 0.5 bar-g was fed. After 1 hour cooling at roomtemperature the steel tank was opened and the wet polymer collected. Thewet polymer was dried in an oven under reduced pressure at 70° C. Thepolymerization conditions and the characterization data of the obtainedpolymers were reported in Table 1.

TABLE 1 Activity met. mmol T time kg/ I.V. T_(m)(II) ΔH_(f) Ex (mg) AlAl/Zr ° C. min yield g (g_(met) * h) dL/g ° C. J/g M_(w) M_(w)/M_(n) 1A-1 (3) 4.42 990 50 60 110 37 1.99 97.3 27 715 600 2.4 2 A-1 (3) 4.42990 70 60 310 103 1.44 92.7 27 356 300 2.1 3 A-1 (3) 4.42 990 80 60 14448 1.23 92.5 26 244 600 2.2  4* A-2 (4) 6.29 990 70 60 50 12.5 0.81102.3. 28 152 500 2.5  5*   A-3 (7.4) 13.6 1060 70 120 244 16.5 0.9591.5 29.5 177 900 2.2 *comparative n.a. = not available

1. A process for preparing 1-butene polymers optionally containing up to 30% by mol of derived units of ethylene, propylene or an alpha olefin of formula CH₂=CHZ, wherein Z is a C₃–C₁₀ alkyl group, comprising polymerizing 1-butene and optionally ethylene, propylene or said alpha olefin, in the presence of a catalyst system obtained by contacting: a) at least a metallocene compound of formula (I):

 wherein: M is an atom of a transition metal selected from those belonging to group 4; p is 2, being equal to the formal oxidation state of the metal M minus 2; X, equal to different from each other, are hydrogen atoms, halogen atoms, R, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ groups, wherein R is a linear or branched, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl or C₇–C₂₀ arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements; R¹, equal to or different from each other, are linear or branched, C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; R², R³ and R⁶, equal to or different from each other, are hydrogen atoms or linear or branched, C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; R⁴and R⁵, form together a condensed saturated or unsaturated C₃–C₇ membered ring optionally containing heteroatoms belonging to groups 13–16 of the Periodic Table of the Elements; every atom forming said ring being substituted with R⁷ radicals wherein R⁷, equal to or different from each other, are hydrogen atoms or linear or branched, C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; L is Si(R⁸)₂ wherein R⁸ is a linear or branched, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl, or C₇–C₂₀ arylalkyl radical; and b) an alumoxane or a compound that forms an alkylmetallocene cation.
 2. The process according to claim 1 wherein the catalyst system further comprises an organo aluminum compound.
 3. The process according to claim 1, wherein in the compound of formula (I), X is a halogen atom.
 4. The process according to claim 1 wherein R¹ is a C₁-C₂₀-alkyl radical; R², R³ and R⁶ are hydrogen atoms and R⁷ is a hydrogen atom or a linear or branched, C₁-C₂₀-alkyl radical.
 5. The process according to claim 1 wherein the compound of formula (I) has formula (IIa) or (IIb):


6. The process according to claim 5 wherein R⁷, equal to or different from each other, are linear or branched, C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13-17 of the Periodic Table of the Elements.
 7. The process according to claim 6 wherein formula I is formula IIa.
 8. The process according to claim 6 wherein formula I is formula IIb.
 9. The process according to claim 1 wherein 1-butene is homopolymerized.
 10. A metallocene compound of formula (IIb):

wherein M is an atom of a transition metal selected from those belonging to group 4; p is 2, being equal to the formal oxidation state of the metal M minus 2; L is Si(R⁸)₂ wherein R⁸ is a linear or branched, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl, or C₇–C₂₀ arylalkyl radical; R¹, equal to or different from each other, are linear or branched, C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; R², R³ and R⁶, equal to or different from each other, are hydrogen atoms or linear or branched, C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; R⁷, equal to or different from each other, are linear or branched, C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; X, equal to different from each other, are hydrogen atoms, halogen atoms, R, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ groups, wherein R is a linear or branched, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl or C₇–C₂₀ arylalky radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements.
 11. A process for preparing a metallocene compound of formula (IIb):

wherein M is an atom of a transition metal selected from those belonging to group 4; p is 2, being equal to the formal oxidation state of the metal M minus 2; L is Si(R⁸)₂ wherein R⁸ is a linear or branched, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl, or C₇–C₂₀ arylalkyl radical; R¹, equal to or different from each other, are linear or branched, saturated or unsaturated C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; R², R³ and R⁶, equal to or different from each other, are hydrogen atoms or linear or branched, saturated or unsaturated C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing one or more heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements; R⁷, equal to or different from each other, are hydrogen atoms or linear or branched, saturated or unsaturated C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; X, equal to different from each other, are halogen atoms, OSO₂CF₃ or OCOR groups, wherein R is a linear or branched, saturated or unsaturated C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl or C₇–C₂₀ arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements; comprising the following steps: a)contacting a ligand of formula (V):

 or its double bond isomer with a base of formula T_(j)B or TMgT¹, or sodium or potassium hydride, or metallic sodium or potassium; wherein B is an alkali or alkaline earth metal and j is 1 or 2, j being equal to 1 when B is an alkaline metal, and j being equal to 2 when B is an alkali-earth metal; T is selected from the group consisting of linear or branched, saturated or unsaturated C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl or C₇–C₂₀ arylalkyl groups, optionally containing at least one Si or Ge atom; T¹ is a halogen atom or a group OR″ wherein R″ is a linear or branched, saturated or unsaturated C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radicals, optionally containing at least one heteroatom belonging to groups 13–17 of the Periodic Table of the Elements; wherein the molar ratio between said base and the ligand of the formula (V) and is at least 2:1; and b) contacting the product obtained in step a) with a compound of formula MX₄. 